334 Heredity and Environment 



tap, great energies upon which we seldom draw, and that we 

 habitually live upon a level which is far below that which we might 

 occupy. Darwin held the opinion, as the result of a lifetime of 

 observation, that men differ less in capacity than in zeal and de- 

 termination to utilize the powers which they have. In playful 

 comment on the variety and extent of his own life work he said 

 in modest and homely phrase, "It's dogged as does it." It may 

 be objected that the zeal and determination were inherited, but 

 here also the hereditary possibilities become actualities only as 

 the result of use, training, the formation of habits. 



It is generally admitted that no constant distinction can be 

 recognized between the brain of a philosopher and that of many 

 a peasant. Neither size nor weight of brain nor complexity of 

 convolutions bears any constant relation to ignorance or intelli- 

 gence, though doubtless an "unlimited microscopist" could find 

 differences between the trained and the untrained brain. The 

 brains of Beethoven, Gauss and Cuvier, although unusually large, 

 have been matched in size and visible complexity by the brains of 

 unknown and unlearned persons persons who were richly en- 

 dowed by nature but who had never learned to use their talents. 

 In all men the capacity for intellectual development is probably 

 much greater than the actuality. The parable of the talents ex- 

 presses a profound biological truth, men differ in hereditary en- 

 dowments, one receives ten talents and another receives but one ; 

 but the used talent increases many fold, the unused remains un- 

 changed and undeveloped. Happy is he who is compelled to use 

 his talents ; thrice happy he who has learned how to compel him- 

 self ! We shall not live to see the day when human inheritance 

 is greatly improved, though that time will doubtless come, but in 

 the meantime we may console ourselves by the thought that we 

 have many half -used talents, many latent capacities, and although 

 we may not be able to add to our inheritance new territory we 

 may greatly improve that which we have. 



Jennings has pointed out as one of the great tragedies of life 

 the almost infinite slaughter of potential personalities in the form 



